While I would agree don't make the general tree overpowered as a rule of thumb, I really do like the idea of having several general trees that all ships can use.
My only worry is, can enough diverse trees be made by doing this?
In previous, more-magical titles you could add a lot of different attack options to fill out the class-specific abiltiies. In Drox, you don't really have that convenience. And, it looks like there are plans to add a LOT of options to each tree.
Either way, can't wait to see how things unfold.